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IPFW(4) FreeBSD Kernel Interfaces Manual IPFW(4)
NAMEipfw -- IP packet filter and traffic accounting
SYNOPSIS
To compile the driver into the kernel, place the following option in the
kernel configuration file:
optionsIPFIREWALL
Other related kernel options which may also be useful are:
optionsIPFIREWALL_DEFAULT_TO_ACCEPToptionsIPFIREWALL_VERBOSEoptionsIPFIREWALL_VERBOSE_LIMIT=100
To load the driver as a module at boot time, add the following line into
the loader.conf(5) file:
ipfw_load="YES"
DESCRIPTION
The ipfw system facility allows filtering, redirecting, and other opera-
tions on IP packets travelling through network interfaces.
The default behavior of ipfw is to block all incoming and outgoing traf-
fic. This behavior can be modified, to allow all traffic through the
ipfw firewall by default, by enabling the IPFIREWALL_DEFAULT_TO_ACCEPT
kernel option. This option may be useful when configuring ipfw for the
first time. If the default ipfw behavior is to allow everything, it is
easier to cope with firewall-tuning mistakes which may accidentally block
all traffic.
To enable logging of packets passing through ipfw, enable the
IPFIREWALL_VERBOSE kernel option. The IPFIREWALL_VERBOSE_LIMIT option
will prevent syslogd(8) from flooding system logs or causing local Denial
of Service. This option may be set to the number of packets which will
be logged on a per-entry basis before the entry is rate-limited.
The user interface for ipfw is implemented by the ipfw(8) utility, so
please refer to the ipfw(8) manpage for a complete description of the
ipfw capabilities and how to use it.
SEE ALSOsetsockopt(2), divert(4), ip(4), ipfw(8), sysctl(8), syslogd(8), pfil(9)
FreeBSD 11.1 October 25, 2012 FreeBSD 11.1